Plant biostimulants are components other than fertilizers that affect plant growth and/or metabolism upon foliar application and/or when added to soil. Plant biostimulants include, but are not limited to, hormone-containing products, amino acid-containing products, and humic acid-containing products. Exemplary plant biostimulants include compositions based on seaweed extract, humic acid, amino acids, salicylic acid, bio-solids, hydrolyzed proteins, silicate, and/or synthetic compounds. Plant biostimulants are used to treat crops in a commercial setting, in part, due to their ability increase growth rates, decrease pest plant growth, increase stress tolerance, increase photosynthetic rate, and increase disease tolerance. Although the precise mechanism by which plant biostimulants exert their effect on plants, one hypothesis is that they operate by up-regulating or down-regulating plant hormones.
Despite advances in agricultural compositions and methods, there remains a need for compositions and methods that can perform plant biostimulation, i.e., improving plant growth responses and development, while reducing the use of chemical fertilizers. Methods and compositions disclosed herein may address these needs and others.